Project Summary: The broad, long-term goal of this project is to develop a wearable high performance MEG system that can operate without external shielding that will lead to Advances in Human Neuroscience and transformative advances in our understanding of the Human Brain ?in Action and in Context?, which are currently unachievable via imaging technologies in live persons. There are two specific aims: Aim 1 is a Small- scale, proof-of-concept development of uMEG Sensors to validate a novel non-invasive contactless uncooled unshielded magnetic sensor system based on total-field optically-pumped magnetometers (tOPM). Aim 2 is a small-scale human study to generate preliminary results with the uMEG system. Here, we will design and validate a closed-loop uMEG-based brain-computer interface (BCI) system in healthy adults. The proof-of- principle prototype system will be the first flexible array of total-field optically-pumped magnetometers (OPMs) that has the potential to enable a truly wearable MEG system for behaviorally active human neuroimaging that allows for movement in space/place during imaging in more natural environments while maintaining high resolution. This system will lead to next generation high-performance non-invasive closed-loop wearable neural interfaces that can be used to control prosthetics, computers and other assistive and therapeutic devices to study, diagnose, repair, augment, or restore cognitive-motor capabilities after brain injury or neurological disease.